首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17715篇
  免费   871篇
  国内免费   155篇
耳鼻咽喉   176篇
儿科学   474篇
妇产科学   174篇
基础医学   2128篇
口腔科学   395篇
临床医学   1086篇
内科学   4919篇
皮肤病学   302篇
神经病学   1090篇
特种医学   768篇
外科学   3102篇
综合类   63篇
预防医学   416篇
眼科学   194篇
药学   1095篇
中国医学   32篇
肿瘤学   2327篇
  2024年   14篇
  2023年   150篇
  2022年   263篇
  2021年   533篇
  2020年   288篇
  2019年   341篇
  2018年   454篇
  2017年   352篇
  2016年   423篇
  2015年   446篇
  2014年   555篇
  2013年   726篇
  2012年   1054篇
  2011年   1224篇
  2010年   671篇
  2009年   581篇
  2008年   1075篇
  2007年   1187篇
  2006年   1080篇
  2005年   1108篇
  2004年   1126篇
  2003年   1039篇
  2002年   1057篇
  2001年   225篇
  2000年   212篇
  1999年   230篇
  1998年   281篇
  1997年   199篇
  1996年   190篇
  1995年   180篇
  1994年   174篇
  1993年   167篇
  1992年   122篇
  1991年   122篇
  1990年   107篇
  1989年   116篇
  1988年   79篇
  1987年   74篇
  1986年   60篇
  1985年   52篇
  1984年   42篇
  1983年   47篇
  1982年   48篇
  1981年   36篇
  1980年   38篇
  1979年   28篇
  1978年   29篇
  1977年   16篇
  1976年   19篇
  1974年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Although anaphylactoid reactions to local anesthetics are well known, a radioallergosorbent test (RAST) to detect specific drug reagin (IgE) anti-body has not been developed. We established RAST for local anesthetics by using carboxylic acid derivatives of lidocaine, procaine and methylparaben. Serum samples were taken from 100 volunteers who were regarded to be nonallergic to the drugs used. Negative RAST values obtained from these volunteers were 1653 ± 254(SD) cpm (lidocaine), 2750 ± 264cpm (procaine), and 2805 ± 336cpm (methyl paraben).(Kokubu M, Oda K, Shinya N: Radioallergosorbent test (RAST) for specific IgE antibody to lidocaine, procaine and methylparaben. J Anesth 3: 74–79, 1989)  相似文献   
23.
24.
We report the results of reduced-intensity unrelated cord blood transplantation (RI-UCBT) in patients with advanced malignant lymphoma. Twenty patients (median age, 46.5 years; range, 27-66 years) underwent RI-UCBT with a preparative regimen consisting of fludarabine 125 mg/m2 , melphalan 80 mg/m 2 , and 4 Gy of total body irradiation. The median infused total cell dose was 2.75 x 10(7)/kg (range, 2.3-3.4 x 10(7)/kg). Graft-versus-host disease (GVHD) prophylaxis was composed of cyclosporine or tacrolimus alone. Fifteen patients achieved primary neutrophil engraftment after a median of 20 days. Eight patients developed grade II to IV acute GVHD, and 2 developed chronic GVHD. Of the 16 patients with evaluable disease, 10 achieved a complete response. Primary disease recurred in 1 patient, and transplant-related mortality within 100 days occurred in 8 of 20 patients. The estimated 1-year probability of progression-free survival was 50%. These data suggest that RI-UCBT is a feasible option for patients with refractory lymphoma who lack an HLA-matched donor.  相似文献   
25.
26.
Pacific Islands populations can be broadly divided into Austronesians (AN) and Non-Austronesians (NAN); obesity and type 2 diabetes are prevalent in the former, although leptin levels in both groups have seldom been investigated. Thirty-seven (20 male and 17 female) adult pairs, matched by age and percent body fat, from AN-speaking Balopa and NAN-speaking Huli, all of whom migrated to settle in Port Moresby, the capital of Papua New Guinea, were selected for comparison of their serum leptin concentrations. The Balopa did not differ significantly from the Huli in age (30.5 +/- 9.7 and 30.0 +/- 8.7 years for males, 33.7 +/- 8.9 and 34.1 +/- 7.5 years for females, respectively) or percent body fat (19.4 +/- 5.6 and 18.8 +/- 4.6 for males, 34.1 +/- 6.2 and 33.3 +/- 5.0 for females), although the BMI of females was lower in the Balopa (26.4 +/- 4.9) than in the Huli (29.7 +/- 4.7) (P = 0.02). In both ethnic groups, females had markedly higher leptin concentrations than males, but there was no significant inter-group difference in males (3.5 +/- 2.6 and 3.1 +/- 4.7 ng/ml, P = 0.14) or females (22.7 +/- 12.9 and 19.7 +/- 11.9 ng/ml, P = 0.40), after controlling for lifestyle factors and serum lipids. Multiple regression analysis revealed that significant predictors of leptin concentration were % body fat (beta = 0.58), sex (male, 0; female, 1; beta = 0.27), and smoker status (non-smoker, 0; smoker, 1; beta = -0.15) (R(2) = 0.80), implying that the leptin concentration was primarily determined by lifestyle-derived body fatness. In conclusion, the NAN populations do not endogenously differ in leptin status from the AN populations, who have been recognized as a typical group with a "thrifty" genotype.  相似文献   
27.
EKLF/KLF1 was the first of the Krüppel-like factors (KLFs) to be identified in mammals and plays an important role in primitive and definitive erythropoiesis. Here, we identify and characterize EKLF in the chicken (cEKLF). The predicted amino acid sequence of the zinc finger region of cEKLF is at least 87.7% similar to mammalian EKLF proteins and is 98.8% and 95% similar to the EKLF orthologues in Xenopus and zebrafish, respectively. During early embryonic development, cEKLF expression is seen in the posterior primitive streak, which gives rise to hematopoietic cells, and then in the blood islands and in circulating blood cells. cEKLF mRNA is expressed in blood cells but not in brain later in chicken embryonic development. cEKLF mRNA is increased in definitive compared with primitive erythropoiesis. The conserved sequence and expression pattern of cEKLF suggests that its function is similar to its orthologues in mammals, Xenopus, and zebrafish.  相似文献   
28.
In order to evaluate the utility of the mouse lymphoma assay(MLA) for detecting in vitro clastogens and spindle poisonsand to compare it with the in vitro chromosomal aberration test(CA), we conducted an international collaborative study of theMLA that included 45 Japanese laboratories and seven overseaslaboratories under the cooperation of the Ministry of Healthand Welfare of Japan and the Japanese Pharmaceutical Manufacturer'sAssociation. We examined 40 chemicals; 33 were reportedly positivein the CA but negative in the bacterial reverse mutation assay,six were negative in both assays and one was positive in both.We assayed mutations of the thymidine kinase (TK) locus (tk)of L5178Y tk+/– mouse lymphoma cells using the microwellmethod. According to our standard protocol, cells were exposedto the chemical for 3 h, cultured for 2 days and TK-deficientmutants were expressed in 96-well plates under trifluorothymidine.Each chemical was coded and tested by two or three laboratories.Among the 34 CA-positive chemicals, positive MLA results wereobtained for 20 and negative results were obtained for nine.The remaining five chemicals were inconclusive or equivocalbecause of discrepant inter-laboratory results or reproduceddiscrepant results, respectively. Among the six CA-negativechemicals, one was negative in the MLA, two were positive andthree were inconclusive. Thus, the MLA could detect only 59%(20/34) of CA-positive chemicals. We concluded that the MLAwas not as sensitive as the CA. Some MLA-negative chemicalsevoked positive responses in the CA only after long continuoustreatment. These might also be genotoxic in the MLA with longcontinuous treatment. Improvement of the MLA protocol, includingalteration of the duration of the treatment, might render theMLA as sensitive as the CA. 8 To whom correspondence should be addressed. Tel: +81 3 37009847; Fax: +81 3 3700 2348; Email: sofuni{at}nihs.go.jp  相似文献   
29.
The HIV/AIDS surveillance system in Japan, which began collecting data on the number of AIDS patients in 1984 and the number of HIV-infected persons in 1987, has played an important role in monitoring the trend and magnitude of Japan's HIV/AIDS epidemic and its distribution across various population subgroups. However, the system lacks any personal identifiers, making it impossible to eliminate duplication or to track cases for disease progression. It also does not permit the identification of the residence of HIV-infected persons because the residence of only the reporting physician is documented under the New Infectious Diseases Control Law, effective since April 1, 1999. The number of people with HIV/AIDS in Japan continues to grow. Among youth, sexually transmitted diseases, induced abortion, and sexual activities have shown a marked increase since the mid-1990s. Behavioral risk of infection for both injection drug users (IDUs) and men who have sex with men (MSM) remains alarmingly high. Accurate monitoring of infection rates is critical to the planning and evaluation of treatment, care and prevention programs. Japan should restructure its HIV/AIDS surveillance system to more accurately monitor the HIV/AIDS epidemic and related risk behaviors.  相似文献   
30.
Invasive fungal infection (IFI) is a significant complication after allogeneic hematopoietic stem cell transplantation (HSCT); however, we have little information on its clinical features after reduced intensity cord blood transplantation (RICBT) for adults. We reviewed medical records of 128 patients who underwent RICBT at Toranomon Hospital between March 2002 and November 2005. Most of the patients received purine-analogbased preparative regimens. Graft-versus-host disease (GVHD) prophylaxis was a continuous infusion of either tacrolimus 0.03 mg/kg or cyclosporine 3 mg/kg. IFI was diagnosed according to the established EORTC/NIH-MSG criteria. IFI was diagnosed in 14 patients. Thirteen of the 14 had probable invasive pulmonary aspergillosis and the other had fungemia resulting from Trichosporon spp. Median onset of IFI was day 20 (range: 1-82), and no patients developed IFI after day 100. Three-year cumulative incidence of IA was 10.2%. Four of the 13 patients with invasive aspergillosis (IA) developed grade II-IV acute GVHD, and their IA was diagnosed before the onset of acute GVHD. The mortality rate of IFI was 86%. Multivariate analysis revealed that the use of prednisolone >0.2 mg/kg (relative risk 7.97, 95% confidence interval 2.24-28.4, P = .0014) was a significant risk factor for IA. This study suggests that IFI is an important cause of deaths after RICBT, and effective strategies are warranted to prevent IFI.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号